Axial-flow type fan having an air inlet blade structure tipped with leading corners

ABSTRACT

An axial-flow type fan includes a fan housing consisting of an air-boosting inlet, an air outlet and an air channel, and a fan wheel consisting of a hub and fan blades arranged about a rotary axis of the hub. Each of the fan blades has a tipped leading corner to constitute an air inlet blade structure which forms a topmost portion in a longitudinal direction and a forefront portion in a rotational direction. The tipped leading corners are situated in the air-boosting inlet of the fan housing while the air channel accommodates the fan wheel. When the fan wheel is rotated, the tipped leading corners of the fan blades are able to eliminate air turbulence and air noise in the air-boosting inlet of the fan housing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an axial-flow type fan having an airinlet blade structure tipped with leading corners. More particularly,the present invention relates to an axial-flow type fan having an airinlet blade structure tipped with leading corners situated in anair-boosting inlet of a fan housing, thereby reducing air-shearing noisein operation.

2. Description of the Related Art

Referring initially to FIG. 1, it illustrates a conventional fan housingstructure having an air outlet connecting with an air inlet. Theconstruction of the conventional fan structure is disclosed in U.S. Pat.Nos. 4,734,015, 4,743,173, Re34,456, 4,806,081, 4,992,029, 5,028,216,5,135,363 and 5,267,842 etc. The fan structure consists of a fan housing10 and a fan wheel (so-called impeller) 20 accommodating therein. Theconstruction of the fan housing 10 is shaped square including an airinlet side (so-called upstream side) 11 and an air outlet side(so-called downstream side) 11′ disposed at its either side. The airinlet forms an air-boosting inlet 12 while the air outlet (not labeled)forming an air-expanding outlet. An air channel 13 connects between theair-boosting inlet 12 and the air-expanding outlet. The fan wheel 20 isaccommodated in the air channel 13, and consists of a hub 21 and aplurality of fan blades 22 arranged about a rotary axis of the hub 21.The construction of the hub 21 is a barrel-shaped object having an outercircumference on which equi-spaced and titled the fan blades 22 each ofwhich forms a flat vane. In operation, when the fan wheel 20 is rotated,the fan blades 22 drives air to suck into the fan, housing 10 throughthe air-boosting inlet 12 that increases the pressure of air inlet.Subsequently, airflow may pass through the air channel 13 and exhaustfrom the air-expanding outlet that steadies an exhausting airflow.

However, there exist several drawbacks of the axial-flow type fan inuse. Each flat vane of the fan blade 22 forms an inlet corner portion221 as well as a flat portion at its endmost corner. The inlet cornerportion 221 of the fan blade 22 is situated in the longitudinal sectionof the air-boosting inlet 12 and almost perpendicular to a surface ofthe air-boosting outlet 12. When the fan blades 22 drive a mass of theinlet air entering through the air-boosting inlet 12, the mass of theinlet air may impact the annular surface of the air-boosting inlet 12that guides the inlet air for entering into the fan housing 10. In theradial section of the air-boosting inlet 12, the flat vane portion ofthe inlet corner portion 221 extends a straight leading edge 220proximate the air inlet side. Also, when the fan blades 22 is rotated,the straight leading edge 220 aggravates the air turbulence generated onthe annular surface of the air-boosting inlet 12 and causes air-shearingnoise. Hence, there is a need for an inlet corner portion of the fanblade for improving air-shearing noise.

The present invention intends to provide an axial-flow type fan havingan air inlet blade structure tipped with leading corners situated in anair-boosting inlet of a fan housing. When the fan is rotated, theleading corners are able to increase air pressure and to reduceair-shearing noise in the air-boosting inlet of the fan housing in sucha way to mitigate and overcome the above problem.

SUMMARY OF THE INVENTION

The primary objective of this invention is to provide an axial-flow typefan having an air inlet blade structure tipped with leading corners,each of which forming a topmost blade portion in a longitudinaldirection, which is situated in an air-boosting inlet of a fan housing,thereby the leading corners reducing air noise.

The secondary objective of this invention is to provide the axial-flowtype fan having the air inlet blade structure tipped with leadingcorners, each of which forming a forefront portion in a rotationaldirection, which is situated in an air-boosting inlet of a fan housing,thereby the leading corners reducing air noise.

The third objective of this invention is to provide the axial-flow typefan having the air inlet blade structure tipped with leading cornersradially approaching an annular surface of the air-boosting inlet andsituated in an air-boosting inlet of a fan housing, thereby the leadingcorners reducing air noise.

The fourth objective of this invention is to provide the axial-flow typefan having the air inlet blade structure tipped with leading corners,each of which including a ridge on a leeward side connecting between aninlet leading corner point and an outlet trailing bottom point tothereby guide airflow.

The axial-flow type fan in accordance with the present inventionincludes a fan housing consisting of an air-boosting inlet, an airoutlet and an air channel, and a fan wheel consisting of a hub and fanblades arranged about a rotary axis of the hub. Each of the fan bladeshas a tipped leading corner to constitute an air inlet blade structurewhich forms a topmost portion in a longitudinal direction and aforefront portion in a rotational direction. The tipped leading cornersare situated in the air-boosting inlet of the fan housing while the airchannel accommodates the fan wheel. When the fan wheel is rotated, thetipped leading corners of the fan blades are able to eliminate airturbulence and air noise in the air-boosting inlet of the fan housing.

Other objectives, advantages and novel features of the invention willbecome more apparent from the following detailed description and theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in detail with reference tothe accompanying drawings wherein:

FIG. 1 is a cutaway cross-sectional view of a conventional fan housingstructure in accordance with the prior art;

FIG. 2 is an exploded perspective view of an axial-flow type fan havingan air inlet blade structure tipped with leading corners in accordancewith a preferred embodiment of the present invention;

FIG. 3 is a top plan view of the axial-flow type fan having the airinlet blade structure tipped with leading corners in accordance with thepreferred embodiment of the present invention;

FIG. 4 is a cross-sectional view, taken along line 4-4 in FIG. 3, of theaxial-flow type fan having the air inlet blade structure tipped withleading corners in accordance with the preferred embodiment of thepresent invention; and

FIG. 5 is a cross-sectional view, similar to that shown in FIG. 4, of anaxial-flow type fan having the air outlet blade structure tipped withleading corners in accordance with the preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 2 through 4, reference numerals of the preferredembodiment of the present invention have applied the identical numeralsof the conventional fan structure, as shown in FIG. 1. The constructionof the fan structure in accordance with the preferred embodiment of thepresent invention has similar configuration and same function as that ofthe conventional fan structure and detailed descriptions may be omitted.

Referring to FIGS. 2 through 4, an axial-flow type fan in accordancewith a preferred embodiment of the present invention includes a fanhousing 10 and a fan wheel 20.

Referring again to FIGS. 2 through 4, the construction of the fanhousing 10 shall be described in detail. The fan housing 10 is made ofplastic or metal material, and formed with a square or circular hollowbody. The fan housing 10 includes an air inlet side 11 and an air outletside 11′ at its either side, as best shown in FIGS. 2 and 4. Further,the fan housing 10 consists of an air-boosting inlet 12, an air channel13, a base 14, a plurality of supporting ribs 15 and an air-expandingoutlet 16. The air inlet side 111 of the fan housing 10 provides withthe air-boosting inlet 12 which is formed with an annular taperedsurface for increasing air inflow and air pressure. The air-boostinginlet 12 further communicates with the air channel 13. Meanwhile, theair outlet side 11′ of the fan housing 10 provides with theair-expanding outlet 16 which is formed with an annular expanded surfacefor increasing air outflow. The base 14 is disposed in the air-expandingoutlet 16 to support a motor stator 30 which is combined with the fanwheel 20 as well as a motor rotor (not labeled), as best shown in FIG.2. The supporting ribs 15 are arranged about a rotary axis of the fanhousing 10, and thus connect between the base 14 and the fan housing 10.

Turning now to FIGS. 2 through 5, the construction of the fan wheel 20shall be described in detail. The fan wheel 20 is made of plastic ormetal material, and consists of a hub 21 and a plurality of fan blades22 arranged about a rotary axis of the hub 21. The construction of thehub 21 is a barrel-shaped object having an outer circumference on whichequi-spaced and titled the fan blades 22 each of which forms a curvevane. The curve vane of each fan blade 22 has a tipped leading corner221′, an inlet bottom point 222, a ridge 223 and an outlet bottom point224. Particularly, each of the fan blades 22 has a tipped leading corner221′ to constitute an air inlet blade structure which forms a topmostportion in a longitudinal direction. Namely, the tipped leading corner221′ of the fan blade 22 is closely aligned with a horizontal plane ofthe air inlet side 11, as best shown in FIG. 4. And the tipped leadingcorner 221′ of the fan blade 22 also forms a forefront portion in arotational direction and is radially approaching an annular surface ofthe air-boosting inlet 12 of the fan housing 10, as best shown in FIG.3. Furthermore, a curved leading edge 220′ of the fan blade 22 extendsalong a curve line connecting between the tipped leading corner 221′ andthe inlet bottom point 222. Regarding the curved leading edge 220′, thetipped leading corner 221′ forms a forefront point, as best shown inFIG. 3. Between the an inlet bottom point 222 and the outlet bottompoint 224, each of the fan blade 22 tilts on the outer circumference ofthe hub 21, as best shown in FIG. 2. Additionally, the ridge 223protrudes on a leeward surface of the fan blade 22 connecting between aninlet leading corner point of the tipped leading corner 221′ and theoutlet bottom point 224, as best shown in FIG. 5.

Referring again to FIGS. 4 and 5, when the fan housing 10 and the fanwheel 20 are assembled, there are several assembled relationshipsbetween the fan housing 10 and the fan wheel 20. First, an inlet leadingcorner point C of the tipped leading corner 221′ is situated between astarting point A and a terminal point B of the air-boosting inlet 12 ina longitudinal direction, thereby precisely reducing air turbulence onthe surface of the air-boosting inlet 12. Second, the leading point C ofthe tipped leading corner 221′ and the position D of the inlet bottompoint 222 are situated on a common plane, thereby the tipped leadingcorner 221′ effectively reducing air turbulence within the air-boostinginlet 12. Alternatively, the leading point C of the tipped leadingcorner 221′ is slightly higher than the position D of the inlet bottompoint 222 in the longitudinal direction, thereby the tipped leadingcorner 221′ effectively reducing air turbulence within the air-boostinginlet 12. By use such an assembled relationship, when the fan blades 22drive a mass of the inlet air entering into the air-boosting inlet 12,the air-boosting inlet 12 compresses the inlet air for increasing airpressure in the air channel 13 of the fan housing 10. Subsequently, theforefront portion of the tipped leading corner 221′ radially approachingthe air-boosting inlet 12 can avoid generating air noise and airturbulence. Meanwhile, the curved leading edge 220′ of the fan blade 22with the tipped leading corner 221′ can eliminate a transverse airflowin the air-boosting inlet 12 when rotated. Also, the ridge 223 of thefan blade 22 can guide airflow in the air-boosting inlet 12, thereby thesmooth airflow exhausting from the air-expanding outlet 16.Consequently, the tipped leading corner 221′ of the fan blade 22 carriesout a preferred air-shearing effect that can reduce air noise in theair-boosting inlet 12 of the present invention.

Referring back to FIG. 1, the conventional axial-flow type fan includesthe air-boosting inlet 12, and the fan blades 22 having the air inletcorner portions 221′ which may cause air turbulence on an innercircumference of the air-boosting inlet 12 of the fan housing 10 thatgenerates air noise. Furthermore, the conventional axial-flow type fanincludes the straight leading edge 220 of the each fan blade 22 whichmay aggravates the air turbulence generated on the annular surface ofthe air-boosting inlet 12. However, as best shown in FIG. 4, the presentinvention employs each of the fan blades 22 having the tipped leadingcorner 221′ proximate the annular surface of the air-boosting inlet 12that may reduce generating air turbulence and air noise. In addition tothe tipped leading corner 221′, each of the fan blades 22 furtherincludes curved leading edge 220′ extending along a curve line in therotational direction, and corresponding to the air-boosting inlet 12that may eliminate a transverse airflow in the air-boosting inlet 12when rotated.

Although the invention has been described in detail with reference toits presently preferred embodiment, it will be understood by one ofordinary skill in the art that various modifications can be made withoutdeparting from the spirit and the scope of the invention, as set forthin the appended claims.

1. An axial-flow type fan, comprising: a fan housing including an airinlet side and an air outlet side at its either side; an air-boostinginlet provided on the air inlet side of the fan housing; an air channelconnecting between the air-boosting inlet and the air outlet side; a fanwheel accommodating in the channel and including a hub; a plurality offan blades arranged about a rotary axis of the fan wheel and tilted onthe hub, and each of the fan blades having an inlet bottom pointconnecting to the hub of the fan wheel; and a plurality of tippedleading corners, each provided on the fan blade to form a topmostportion in a longitudinal direction of the fan housing and a forefrontportion in a rotational direction of the fan wheel, the tipped leadingcorner situated in the air-boosting inlet and including a curved leadingedge connecting between an inlet leading corner point of the tippedleading corner and the inlet bottom point; wherein when the fan wheel isrotated, the tipped leading corners of the blades are able to eliminateair turbulence and air noise in the air-boosting inlet of the fanhousing.
 2. The axial-flow type fan as defined in claim 1, wherein theair-boosting inlet forms with an annular tapered surface along thelongitudinal direction of the fan housing.
 3. The axial-flow type fan asdefined in claim 1, wherein each of the fan blades further includes anoutlet bottom point so that the fan blade tilts between the inlet bottompoint and the outlet bottom point of an outer circumference of the hub.4. The axial-flow type fan as defined in claim 3, wherein the each ofthe fan blades further includes a ridge protruded on a leeward surfaceof the fan blade connecting between an inlet leading corner point of thetipped leading corner and the outlet bottom point, thereby the ridgestabilizing airflow.